Are you sure you cannot simply opt out while registering the sample? I live in Germany and I can only use these kinds of analyses for ethnicity/heritage analysis since genetic testing of risk factors as therelike are forbidden here. But I remember myheritage (which I used) asked me a lot of questions on how much data I want to share, what I want to share anonymously, what I want to share for research or keep in the database or sample storage for future analyses. I was also able to absolutely delete all data - account, sample destruction, genetic data - from every database. Comes with the obvious caveat that you cannot access any data from your initial analysis anymore but in my situation that was an ok trade off.